Optometer



(No Mode l.)

- A. A. T ROWBR IDG'E.

OBTOMETBR.

No. 276,732. Patented May 1,1883.

7 UNIT D STATES PATENT OFFICE,

ALFRED A. TRO'W'BRIDGE, OF DANBURY, CONNECTICUT.

OPTOMETER.

SPECIFICATION forming part of Letters Patent No. 276,732, dated May 1,1883. Application filed February 16, 1883. (No model.)

To all whom it may concern:

BeitknoWnthat1,ALFRED A.TROWBRIDGE, of Danbury, Fairfield county, andState of Con necticut, have invented a new and Improved Optometer,ofwhich the followingis a full, clear, and exact description.

The object of my invention is to provide a new and improveddcvice forascertaining the proper correction or remedy for those defects of sightwhich can be remedied by convex or concave spherical lenses.

This invention, which is an improvement on the optometer for whichLetters Patent No. 262,151 were issued to me August 1, 1882, consists invarious novel parts and combinations of the same, as will be fullydescribed herein- 1 after.

' ing shown in longitudinal elevation.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar letters of reference indicatecorresponding parts in all the figures.

Figure 1 isa longitudinal elevation of the outer side of thclens-holdingface-plate. Fig. 2 is a cross-sectional elevation of the same on theline a: 00, Fig. 1, the hood and scale-rod be- Fig. 3 is a front view ofthe sight-card.

The face-plate A is provided with two apertures, B B, the centers ofwhich are on a horizontal line, and are of such diameter and such adistance apart that the portion of the plate between the apertures B Bwill not obstruct the vision of the type or test card when it is nearesttheface-plate. The face-plate A is provided with a vertical and groovednoseopeuing, 0, between and below the apertures B B, thus permitting theplateA to be held closely against the face, the nose passing into thegroove and opening 0.

A hood, D, made of leather, pasteboard, fabric, or any other suitablematerial, and litting closely to the face, is attached to the faceplateA, and serves to exclude the light from the inner side of the face-platewhen the same is set before the eyes and close to the face. Theeye-apertures B B are beveled from the inner toward the outer surface ofthe face-plate A, as shown in Figs. 1 and 2.

In each aperture B there is fixed, near the inner surface of the plateA, a convex sphericallens, E, having a focal length oftwelve inches. i

Adisk or frame, F, made of metal orof other suitable material, and ofsufficient size to cover either of the eye-apertures B B, and holding aconvex spherical lens, G, having a focal length of six inches, isfastened to a springstrip, H, which is pivoted to the outer side of thefaceplate A, between and above the apertures B, so that either of theapertures B can be cov- 6o ered by the said lens. The spring-strip H ispivoted to the plate A at such a distance from the centers of theapertures B that when the lensholding frame F rests against either sideof a check-pin, 0, between the eye-apertures B, '6 the center of thelens G held in the frame F will be opposite the center of one of thelenses E in the face-plate A. Spherical lenses having other focallengths than those named above may be chosen for the same purpose; butthose 0 named will prove the most satisfactory. An opaque disk orshield, L, of sufficient size to cover the lens-holding frameF, isprovided with a handle, M, and is fastened to a spring-strip, N, pivotedon the same pivot as the spring-strip of the frame F. The lensholdingframe F and the opaque shield L are so constructed and. arranged thatthe shield L may be easily raised and turned, so as to cover the frameF, the spring-strip M pressing the shield L against the face of theframcF, which 1 is provided with raised spring clamps orguards it along theperiphery for the purpose of bolding the shield L on the said frame.When the shield L and the frame or disk F are thus 8 placed they may beturned to cover eithereyeaperture B by means of the handle M, as thoughthere were but one disk or shield. The lens-holding frame F being largeenough to cover either of the eye-apertures B, and the 0 opaque shield Lbeing large enough to cover the frame F, they will, when resting againsteither side of the cheek-pin O, entirely exclude the light from thefront of the eye-aperture over which they rest. When the shieldLand thedisk F are held above the eye-apertures-- that is, in such a manner thatthey cover neither-botheyes can be tested by the lens in the aperturesat the same time. When the shield L and the frame F are turned so as towe cover one of the eyeapertures the eyes may be tested separately bythe lens in the apertures B, the light from in front of the face plate Abeing prevented from entering theother eye, which is behind theeye-aperture B that is covered by the frame and shield. The constructionand arrangement of thelens-holding frameF and the opaque shield L alsoallows the lens-holding frame F to be turned so as to cover one of theeye-apertures B andthe opaque shield L so as to cover and exclude thelight from the front of the other eye-aperture B, thus permitting eithereye to be tested by the combined power of the lens in either eyeapertureB and the lens in the lens-holding frame F, all light from the front ofthe faceplate A being thus prevented from entering the eye behind theeye-aperture covered by the opaque disk or shield. The plate A isattached to a frame, P, provided with a handle, Q, from which frame arod, It,-projects in the direction of the outer side of the plate A, andthe said rod is provided with an inch scale, or may be provided with anyother suitable scale indicating the number of lens.

A sliding card-carrier, S, provided with a pointer, S, is looselymounted to slide on the rod It, and carries the type or test card T.(Shown in Fig. 3.) This card is about six by four inches in size, and onthe middle line of the card, under the word both, is placed a series oftest types or objects, which cover a space of about one by one andone-fourth inch, Any suitable object or test may be chosen for thispurpose, but those given are the most practically useful, as they may beprinted from type obtainable in any printing establishment. The smallesttest-objects used on the test-card T are words and disconnected lettersprinted from pearl type. The largest test-objects used on the card areprinted with type three times the size of the pearl type. On the backside of the test-card T. are two series of test-objects, which are thesame in size and arrangement as those on the v face of the card, exceptthat instead of being placed in the middle they are at the ends of thecard, one being at the'right-hand and the other at the left-hand end,and both being marked accordingly. The type on the face of the test-cardT under the word both are used when both eyes arebein g tested together,and when the eyes are being tested singly the card. is reversed on thecard-carrier.

The construction and arrangement of my optometer, as explained and setforth above, may be modified in the following manner: Instead of thesingle lens-holding frame F, pivoted to the face-plate A, so as to beswung over either of the eye-apertures B, two lensholding frames of thesame kind and form as the frame F may be used, but so pivoted to theface-plate A that one of the lens-holding frames may be turned or swungso as to cover one of the eyeapertures B, and the other lensholdingframe turned so as to cover the other eye-aperture, thus allowing botheyes [to be tested at the same time by the combined'powerof the lensesinthe eye-apertures B and thelenses in the frames F. Instead of pivotingthe lens-holding frame to the face-plate, as described above, they mayeach be attached to the face-plate by a joint or hinge, which will allowthem to be turned down upon the faceplate, so as to cover theeye-apertures, or to be turned back out of the way, as desired.

The instrumentis used in the following manner: The person whose eyes areto be tested holds the optometer by the handle Q, close to the face, thenose passing into the opening 0. If both eyes are to be tested togetherby means of the lenses E fixed in the face-plate A, the shield L isturned. so as to cover the disk F, and both the shield and frame areturned so as to rest above and between the eye-apertures B. If each eyeis to be tested separately by means of the lens E, the shield L andframe F are together turned down, so as to cover either aperture, asdesired. If each eye is to be tested separately by means of the combinedpower of one lens E and the lens'in the frame F, the said frame isturned so'as to cover either aperture B, as desired, and the shield L isturned so as to cover the otherapertnre B.

Having thus described my invention, Iclaim as new and desire to secureby LettersPatent 1. In an optometer, the combination, with aneye-apertured face-plate adapted to hold lenses, of a lens held in aframe pivoted to lens can be swung over either of the eye-apertures,substantially as herein shown and described, and for the purpose setforth.

2. In an optometer, the combination, with t the eye-apertured face-plateA, of the frame F, carrying a lens, G, and pivoted to the. faceplate,and of the stud 0,between the eye-apertures of 'the'faceplate,substantially as herein shown and described, and for the purpose set 1forth.

3'. In an optometer, the combination, with an eye-apertured face-plate,of a frame holdving a lens and pivoted to the face-plate, and

of an opaque disk pivoted to the face-plate, and adapted to swing overeither eye-aperture and over the lens held in the pivoted frame,substantially as, herein shown and described, and for the purpose setforth.

4. In an optometer, the combination, with the eye-apertured face-plateA, of the frame F, holding the lens G, and pivoted to the faceplate A,and of. the disk L, pivoted to the faceplate A, and provided with thehandle M, substantially as herein shown and described, and for thepurpose set forth.

5. In an optometer, the combination, with the eye-apertured face-plateA, of the frame F, pivoted to the face-plate holding a lens, G

and provided with spring-clamps n, and-of the disk L, pivoted to theface-plate, substantially as herein shown and described, and for thepurpose set forth.

6. In an optometer, the combination, with the eye-apertured face-plateA, of the frame.

F, holding alens, G, the spring H, attached to the frame F, and pivotedto the face-plateA, the disk L and the spring N, attached to the disk Land pivoted to the face-plate, substan- 'the face-plate in such a mannerthat the said tially as herein shown and described, and for the purposeset forth.

7. In an optometer, the combination, with the eye-apertured face-plateA, having the lenses E, the grooved nose-opening O, and the hood D, ofthe shield or disk L, the frame 1, scale-rod R, and card-carrier S,substantially as herein showna'nd described, and for the purpose setforth.

8. In an optometer, the combination, with the eye-apertured face-plateA, having the lenses E, the grooved nose-opening C, and the hood D, ofthe frame P, the scale-rod R, and

